Certain chemically inert, fluorinated organosilicon compounds which find utility as hydraulic fluids, release materials, lubricants and as components in greases, inter alia, are disclosed in U.S. Pat. No. 5,110,973 to Caporiccio, said patent being assigned to the assignee of the present invention and hereby incorporated by reference. The compounds taught by Caporiccio combine the desirable properties of tetraalkylsilanes and organic polymers containing fluorinated substituents and these compounds represent a new class of materials wherein a majority of the organic groups bonded to silicon are derived from alkylene-terminated telomers and/or cotelomers of selected fluoroolefins. However, the methods suggested by Caporiccio for preparing these novel compounds rely largely on the conversion of the corresponding halogen-functional perfluoroalkyl halide (iodide or bromide) to a metal (e.g., magnesium or lithium) compound. Unfortunately, these metalloorganic methods for preparing the fluorinated organosilicon compounds have been found to be relatively inefficient when the silicon atom has two or three alkyl groups attached thereto such that they do not provide a high yield of the desired, further alkylated products. For example, when an intermediate containing the structure --Si(Cl.sub.2)--R.sup.3 --Si(Cl.sub.2)--, in which R.sup.3 is a divalent organic group, is reacted with a Grignard reagent of the form R.sub.f MgI, in which R.sub.f is a fluorinated alkyl group, the yield is quite poor if the R.sub.f group is large. Furthermore, when each silicon atom of the intermediate is already bonded to one such R.sub.f group, as in structures of the type --Si(Cl)(R.sub.f)--R.sup.3 --Si(Cl)(R.sub.f)--, reaction with a second Grignard reagent of the form R.sup.2.sub.f MgI to add the group R.sup.2.sub.f is still more difficult, even if the group is small and the reaction is carried out under the preferred low temperature conditions. This situation is somewhat improved when the perfluoroalkyl group is added by employing a lithium compound of the type LiR.sub.f but is still relatively inefficient. The observed yields are not much improved when the desired product is of the form R.sup.1.sub.4 Si wherein R.sup.1 is a monovalent group derived from a fluorotelomer or fluorocotelomer, as defined in the above cited patent to Caporiccio.